1. Field of the Invention
The present invention relates to display devices, user interfaces of the display devices, and methods for providing menus on the display devices. In particular, the present invention relates to a display device, a user interface of the display device, and a method for providing menus on the display device that can be suitably used for a user interface related to the manipulation of menus of what is called a dual view display configured so that different images can be viewed on one display screen from different viewing directions.
2. Description of the Related Art
Dual view displays configured so that different images can be viewed on one display screen from different viewing directions are known (see for example, see Japanese Unexamined Patent Application Publication No. 2005-71286). For example, when a dual view display is used as an in-vehicle display device of a car navigation system, navigation information can be displayed on the side of a driver, and television images, digital versatile disk (DVD) images, and the like can be displayed on the side of a passenger.
Methods for implementing dual view displays include methods using parallax barriers and methods using lenticular lenses. FIG. 8 shows the principle of a dual view display using parallax barriers. The dual view display includes a combination of a switch liquid crystal 101 and a thin film transistor (TFT) liquid crystal 102, as shown in FIG. 8.
A plurality of optical parallax barriers 103 is provided at regular intervals in the switch liquid crystal 101. The parallax barriers 103 control the traveling directions of light beams (backlight for the liquid crystal) so as to separate the light beams into different light beams that reach a left-side viewing position 106 and a right-side viewing position 107. In the TFT liquid crystal 102, an image for the left side and an image for the right side are respectively displayed on a pixel group 104 for the left side and a pixel group 105 for the right side disposed alternately.
Light beams that pass through the parallax barriers 103 and the pixel group 104 reach the left-side viewing position 106, and light beams that pass through the parallax barriers 103 and the pixel group 105 reach the right-side viewing position 107. In this arrangement, different images can be viewed on a display screen of the TFT liquid crystal 102 from different viewing directions.
In some devices in which liquid crystal display panels are used, images displayed on the liquid crystal display panels can be controlled by manipulating not only remote controllers but also touch panels. A touch panel is attached on the front face of a liquid crystal display panel, and operation control by touch can performed by touching a bar, a key switch, or the like, corresponding to a command to select an operation displayed on the liquid crystal display panel.
A touch panel is applicable to the aforementioned dual view display. However, in this case, in addition to a function of displaying separate images on the left and right sides, which characterizes the dual view display, a function of enabling a driver and a passenger to independently perform operations on images displayed individually for them is required. Moreover, a function of determining which of a driver and a passenger has touched the touch panel and adapting the operation of the touch panel to images viewed by the driver or the passenger is also required.
In this case, a method may be adopted, in which a switch for adapting the operation of the touch panel to images viewed by a driver or a passenger, is provided in the main unit to enable the operation of the touch panel by either the driver or the passenger. However, in such a method, since the switch needs to be operated every time a driver or a passenger performs the operation of the touch panel, the operation is complicated.
Moreover, another method may be adopted, in which a sensor that detects the motion of an object is provided at a predetermined place in a vehicle cabin to detect from which of the driver's seat side and the passenger's seat side the touch panel is operated, and it is determined, on the basis of the result of the detection, which of a driver and a passenger has touched the touch panel. However, in such a method, special techniques, such as those implementing a sensor, need to be used, thereby increasing the costs.
In view of the aforementioned problems, in a dual view display described in Japanese Unexamined Patent Application Publication No. 2005-71286, an arrangement is provided to readily and reliably determine which image a touch operation is directed to. In this dual view display, a first touch area is dedicated to a viewer A and a second touch area is dedicated to a viewer B on the touch panel. It is then determined which of these touch areas has been touched, and an operation menu for controlling images corresponding to the touch area, which has been touched, is displayed. However, in the technique described in Japanese Unexamined Patent Application Publication No. 2005-71286, the touch panel needs to be touched once to display the operation menu. Thus, an unnecessary, cumbersome touch operation needs to be performed first.